In recent years,
the number of people affected by coeliac disease, wheat allergy or gluten or
wheat sensitivity has risen sharply. But why is this the case? Could it be that
modern wheat varieties contain more immunoreactive protein than in the past?
Results from a study by the Leibniz-Institute for Food Systems Biology at the
Technical University of Munich and the Leibniz Institute of Plant Genetics and
Crop Plant Research are helping to answer this question.
Wheat grains contain about 70 percent starch. Their
protein content is usually 10 to 12 percent. Gluten accounts for the lion’s
share of proteins, at around 75 to 80 percent. Gluten is a compound mixture of
different protein molecules. These can be roughly divided into two subgroups:
“gliadins” and “glutenins.”
It has long been known that wheat proteins can trigger
disorders such as coeliac disease or wheat allergies. Approximately 1 or 0.5
percent of the adult population is affected worldwide. In addition, non-celiac
gluten sensitivity (NCGS) is becoming increasingly important in the western
world.
“Many people fear that modern wheat varieties contain
more immunoreactive proteins than in the past and that this is the cause of the
increased incidence of wheat-related disorders,” says Darina Pronin from the
Leibniz-Institute for Food Systems Biology, who was significantly involved in
the study as part of her doctoral thesis. Where gluten is concerned, the
protein group of gliadins in particular is suspected of causing undesired
immune reactions, explains the food chemist.
60 wheat varieties from the period 1891 —
2010 analyzed
But how big are the differences between old and new
wheat varieties really? In order to help clarify this, Katharina Scherf and her
team at the Leibniz-Institute for Food Systems Biology investigated the protein
content of 60 preferred wheat varieties from the period between 1891 and 2010.
This was made possible by the Leibniz Institute of Plant Genetics and Crop
Plant Research. It has an extensive seed archive. From the archive, the
researchers selected five leading wheat varieties for each decade of the 120
years examined. In order to generate comparable samples, they cultivated the
different varieties in 2015, 2016 and 2017 under the same geographical and
climatic conditions.
Analyses by the team of scientists show that, overall,
modern wheat varieties contain slightly less protein than old ones. In
contrast, the gluten content has remained constant over the last 120 years,
although the composition of the gluten has changed slightly. While the proportion
of critically viewed gliadins fell by around 18 percent, the proportion of
glutenins rose by around 25 percent. In addition, the researchers observed that
higher precipitation in the year of the harvest was accompanied by a higher
gluten content in the samples.
Environmental conditions are more relevant
than the variety
“Surprisingly, environmental conditions such as
precipitation had an even greater influence on protein composition than changes
caused by breeding. In addition, at least on the protein level, we have not
found any evidence that the immunoreactive potential of wheat has changed as a
result of the cultivation factors,” explains Katharina Scherf, who is now
continuing her research as a professor at the Karlsruhe Institute of Technology
(KIT). However, Scherf also points out that not all protein types contained in
wheat have been investigated with regard to their physiological effects.
Therefore, there is still a lot of research to be done.
Source: https://myfusimotors.com/2020/08/11/gluten-in-wheat-what-has-changed-during-120-years-of-breeding/
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